1. Field of the Invention:
The invention concerns a snap locking device for a container with a cover, said cover being lockable to the container via a flange which is formed on the cover or the container and which may be caused to assume a loosened and a locked position, respectively, and is adapted to cooperate with a locking edge on the container or the cover, the loosening flange, which is thus bistable, being formed with substantially vertical weakened lines.
2. Discussion of the Art:
Containers of such a type are known e.g. from the French Patent Application No. 2 377 333 which concerns the principle of locking devices comprising bistable components. However, such a simple closing arrangement for packages above a certain size is not sufficient when a package is to be used for storing both high-viscous and low-viscous substances. These may be e.g. food products, such as butter, margarine, or jam, and paint, or they may be substances for use in the medical and pharmaceutical industries.
The Danish Published Application No. 145 194 describes a container/cover structure which operates with a bistable locking flange. However, this is a structure which has been found not to be stable in transport, storage and stacking. Further, the package is not provided with a seal device, which is increasingly demanded by many buyers.
The Danish Patent Application No. 3870/83 concerns a package which is formed with seal, but constructed in such a manner as to operate upon rupture of vertical wall constrictions; however, it has been found that this form of seal has a poor control function because the wall constrictions have very little information value. The information value of the seal state is particularly essential in the pharmaceutical industries, and in the other fields of use there is a tendency for more stringent demands on the opening and closing mechanism of packages.